Grid construction



I Dec. 11, 1934. D Y mm 1,984,160

GRID CONSTRUCTION Filed Sept. 9, 1932 Jr 2: z

INVENTOR DOUG LAS SMITH ATTORNEY Patented Dec. 11, 1934 UNITED STATES GRID CONSTRUCTION Douglas Y. Smith, East Orange, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application September 9, 1932, Serial No. 632,297

Claims.

This invention relates to an improvement in electron discharge tubes and more particularly to a novel grid construction for use therein.

Often considerable difficulty is experienced because of primary electron emission from the control grid due to excessive heat developed within the tube after continued operation. As a result the tube begins to operate erratically and much of its efficiency is lost.

It is an object of the present invention to reduce to a minimum grid emission.

Another object or the invention is to provide a grid which under normal conditions of tube operation will remain sufficientlycool to prevent harmful primary emission.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, in which- Fig, 1 illustrates the grid construction according to the invention, and

Fig. 2 shows a plan view of the grid shown in Fig. 1.

Figure 3 shows a front view, with parts broken away, of an electron discharge tube incorporating the grid construction shown in Figure 1.

' Referring to the drawing, the grid is shown as comprising a pair of side rods 1, preferablyof heavy copper, fastenedv at one of their ends 1 novel grid structure described above.

to lead wires 2 passing through the usual press 3. At their other ends the copper rods extend for some distance above the grid wire turns 4 carried by said copper rods and either welded to or embedded in the copper rods, in the usual way so that each grid turn is in intimate metallic engagement with and in good thermal conductive relation to the copper rods. A carbonized circular or other suitably shaped plate 5 is fastened to the extended copper rod portions which project beyond the upper end of the anode or other electrodes surrounding the grid. The combination of the highly conducting copper rods and the highly radiating black "stove pipe outside of the anode in a favorable position for radiating heat freely serves to rapidly radiate the heat from the grid structure and to keep the same sufliciently cool to prevent harmful electron emission.

In the copending application of E. W. Herold, Ser. No. 632,285, filed September 9, 1932, and assigned to the same assignee, is shown a tube construction which has incorporated therein the In the design of this tube it is necessary that the size of the copper rods be determined as part of the I adaptable to the scree pended claims.

' said cathode and anode and comprising a pair of design adopted, inasmuch as they effect the electrical characteristics of the tube.

It is desirable that the radiator or stove pipe be as highly radiating as possible, that is, be black and that it be of such a form that it can 5 be readily heated and degasified by the high frequency currents induced during exhaust.

The tube assembly shown in Figure 3 is similar to the tube assembly shown in Figure 4 of the E. W. Herold copending application, supra. The tube comprises essentially an enclosing glass envelope 6, and a stem '7 which supports a plate electrode 8, a screen grid 9, a control grid 10 having large diameter copper side rods 1 and a carbonized cylindrical shaped radiating member 5 as shown in Figure 1, and a unipotential cathode 11 containing a heater element 12. Although the grid assembly of this invention is particularly grid type of tube illustrated in Figure 3 where a large cathode is positioned in close proximity to the control grid, the invention may be applied equally as well to triode tubes or to other multigrid tubes to prevent grid emission.

While I have shown and described the preferred embodiment of my invention, it is, of course, understood that other structural arrangements may be used without departing from the scope of the invention as covered in the ap- What is claimed is:

1. A grid structure for an electron discharge tube comprising a pair of heavy copper support rods, grid wire turns mounted on said support rodsfand a black coated metal plate carried at one end of said copper rods for dissipating the heat developed in the support rods and grid turns.

2. An electron discharge device comprising an envelope and a plurality of electrodes including a grid comprising a pair of support rods around which a helical grid wire is wound, and a black coated metal plate carried by said support rods.

3. An electron discharge device comprising an envelope having a press therein and a plurality of electrodes including a grid comprising a pair of copper support rods having one of their ends embedded in said press, a helical grid wire wound around said support rods above the press, and a black coated cylindrical metal plate carried by the copper rods at their other ends.

4. An electron discharge device comprising an envelope having a press and enclosing a thermionic cathode, a tubular anode surrounding said cathode, and a grid electrode interposed between metallic supports embedded at one end in said press to project side by side from said press, each of said supports consisting at least in part of a heavy copper rod between said cathode and anode, and a grid wire wound over said copper rods into a helix with its turns in intimate metallic contact with said copper rods.

5. An electron discharge device comprising an envelope having a press and enclosing a thermionic cathode, a tubular anode surrounding said cathode, and a grid electrode interposed between said cathode and anode and comprising a pair of copper support rods above said press and each having one end in good thermal conductive relation to said press and its other end projecting gagement with a side of said strip throughout the 10 width of said strip.

DOUGLAS Y. SMITH. 

